Genomic Instability

工作概述：基因组的不稳定性有几个原因。这些问题包括DNA修复、转录和复制。它们还包括DNA拓扑代谢的缺陷，这是由许多DNA代谢酶控制的。其中一组是拓扑异构酶，我们对它们的功能很感兴趣，因为它与DNA损伤的处理有关。最近的几项研究表明，人类拓扑异构酶I （htopoI）可以识别各种DNA病变，从而形成共价拓扑异构酶I-DNA复合物，已知这对细胞有害。我们已经研究了htopi是否能识别另一个共价捕获在DNA底物上的htopi。为此，我们创造了一种人工DNA底物，其中含有特定的拓扑异构酶I结合序列，其中酶被捕获在共价结合形式中。我们证明，在体外，游离的htopi刺激在共价结合的拓扑异构酶i上游形成额外的切割复合体。我们还研究了群体水平上的基因组不稳定性以及这种不稳定性如何随着年龄的增长而变化。这是在巴尔的摩衰老纵向研究中登记的人的DNA中完成的。在这里，我们测量了一些DNA修复基因的多态性，以确定是否随着衰老或与年龄相关的疾病而发生显著变化。特别是，我们已经集中在基因多态性的人类早衰障碍，维尔纳综合征。到目前为止，我们还没有观察到特定多态性与年龄相关疾病之间的任何联系，但只有少数多态性被研究过，我们计划研究更多的多态性

Summary of work: Genomic instability arises from several sources. These include problems with DNA repair, transcription and replication. They also include deficiencies in the topological metabolism of DNA, which is controlled by a number of DNA metabolic enzymes. A group of these are topoisomerases, and we have been interested in their function as it relates to the handling of DNA damage. Several recent studies have shown that human topoisomerase I (htopoI) can recognize various DNA lesions and thereby form a covalent topoisomerase I-DNA complex, which is known to be detrimental to cells. We have investigated whether htopoI recognizes another htopoI that is covalently trapped on a DNA substrate. For this purpose we created an artificial DNA substrate containing a specific topoisomerase I binding sequence, where the enzyme was trapped in the covalently bound form. We demonstrate that, in vitro, free htopoI stimulates the formation of an additional cleavage complex immediately upstream of the covalently bound topoisomerase I. We also study genomic instability at the population level and how this changes with aging. This is done in DNA from humans enrolled in the Baltimore Longitudinal Study on Aging. Here we measure a number of polymorphisms in DNA repair genes to determine if there are significant changes with aging or with age-associated diseases. In particular, we have focused on polymorphisms in the gene for the human premature aging disorder, Werner syndrome. So far we have not observed any connections between specific polymorphisms and age associated diseases but only a few polymorphisms have been examined, and we plan to look at many more